How they make quark soup in Dubna
At the end of 2024, they plan to launch NICA in Dubna (Nuclotron-based Ion Collider fAcility) is a superconducting collider of protons and heavy ions. The device should help scientists obtain quark-gluon plasma (we will explain what it is later). For the development of one of the key elements of the accelerator, superconducting magnets, Deputy Director for Research at the Laboratory of High Energy Physics of the Joint Institute for Nuclear Research (JINR) Hamlet Khodjibagiyan received the Challenge Prize in the Engineering Solution nomination (by the way, Gazprombank is among the co-founders of the prize). We talked to the scientist and together figured out why it is necessary to obtain quark-gluon plasma and what else superconducting magnets will change in the future.
Let's start at the very beginning. According to modern scientific ideas, our Universe arose about 13 billion years ago as a result of the Big Bang. In the first moments after the event, all matter was in a special state known as quark-gluon plasma, or “quark soup”, or “chronoplasm”. As the Universe expanded and cooled, this plasma formed the particles we are familiar with today. This short period (from 0.000001 to 1 microsecond) of the early Universe is the subject of study of modern physicists.
Why is this important? The study of chronoplasm allows scientists to better understand the first moments of our Universe, to study the fundamental laws of the structure of matter at the deepest level and to observe how the transition from quark-gluon plasma to nuclear (i.e. ordinary) matter, the so-called phase transition, occurs.
By comparison, at temperatures in “colder” plasmas, such as those found in stars or lightning, atoms lose or gain electrons, creating a “soup” of positively and negatively charged ions and free electrons. In the much hotter quark-gluon plasma, the destruction of matter goes deeper: protons and neutrons decay into their constituent quarks and gluons. Hence the name, quark-gluon plasma.
To recreate the conditions of the early universe, scientists use particle accelerators to smash atomic nuclei or subatomic particles together at speeds close to light, briefly creating tiny regions of extremely high energy density in which quark-gluon plasma can form.
To give you a sense of scale, the regions where chronoplasm can form occur for about one yoctosecond (0.000000000000000000000001 of a second, or one ten-trillionth). This is a very short period of time: in a yoctosecond, light has time to travel a distance roughly equal to the size of an atomic nucleus.
By studying the process of quark soup cooling down to ordinary matter, physicists hope to shed light on the earliest stages of the evolution of our universe, which occurred just a few microseconds after the Big Bang. It is a kind of “time machine” that allows us to look into the distant past and better understand how our world came into being.
In fact, this is what they will do at the NICA collider. Scientists want to learn and understand more deeply the fundamental laws of the structure of matter, to study its emergence from quark-gluon plasma. The main goal of the research is to see the so-called phase transition, or the transformation of quark-gluon matter into nuclear (that is, into “ordinary”) matter.
How the collider works and what role do magnets play
How to collide particles with each other, and at relativistic speeds? If you just send them into free flight, they will move in a straight line and uniformly. The solution is to use magnets to hold the particle beam on a circular trajectory. In essence, accelerators consist of two parts: the accelerating sections of the collider accelerate the particles, and the magnetic ones hold them on the trajectory. For example, the NICA collider design uses 370 magnets.
Magnets of different types are used there: dipole magnets create a uniform magnetic field and hold particles in a ring orbit, quadrupole and multipole magnets create a complex magnetic field. With the help of such fields, scientists focus and correct the flow of particles.
The field of the dipole magnets is directed perpendicular to the movement of the particle beam. Its main function is to bend the trajectory of the charged particles, forcing them to move in a circular orbit inside the accelerating ring.
The work of quadrupole and multipole magnets can be compared to the work of an optical system. The former focus a particle beam, acting as a kind of lens, while the latter, creating more complex magnetic fields, help to correct its movement, getting rid of, for example, chromatic aberrations (yes, this term is used not only in optics, but also in the physics of charged particle beams).
Why not accelerate the particles in a straight line? Because the distance over which it would be possible to accelerate the flow of particles to the required speed would be too great, and the length of such an accelerator would be greater than the distance from the Earth to the Sun.
To create the required type of fields, an electric current of about 10,000 amperes is passed through the magnets. For comparison, this is about 100 times greater than in a high-voltage power line.
Due to the high current, a regular magnet is not suitable for use in a collider – it would generate so much heat that it would simply melt. Therefore, installations like NICA use special superconducting magnets. These are entire magnetic-cryostat systems in which the superconducting windings of the magnet are cooled to ultra-low temperatures using a coolant. In the NICA collider, the role of the coolant is performed by a stream of boiling helium with a temperature of 4.6 kelvin (-269 ºC).
Superconducting magnets in the collider are mainly used to keep the particle flow “on track”. In addition, the collider system includes special induction energy storage devices. These devices, which also use superconducting technologies, are capable of accumulating and quickly releasing large amounts of energy. In them, the current passing through the superconducting coil creates a strong magnetic field in which the stored energy is accumulated. When a powerful current pulse is needed, for example, to excite the magnets of the collider's pre-accelerators – the Booster or Nuclotron synchrotrons, the current in the coil is reduced, and the energy stored in the magnetic field is released in the form of the required pulse.
Design Complexities
The magnets used in the collider are highly complex engineering structures that cannot be simply bought. They must withstand enormous currents and create extremely strong magnetic fields, while remaining superconducting at extremely low temperatures. Therefore, a whole specialized workshop for the serial production of the necessary magnets was created in Dubna for the NICA project.
First, design engineers and technologists develop a technology for manufacturing a model magnet. This stage includes calculations, modeling, and creating a prototype. Then the prototype undergoes a series of rigorous tests: magnetic, electrical, and cryogenic. Only if the magnet successfully passes all these tests is its design approved for serial production.
However, ready-made magnets cannot be used at full power right away. Before installation, they need to be “trained”. This is a process in which magnets are gradually supplied with a current of increasing strength. Such training allows it to reach target values without the risk of damage.
If you skip this step and immediately apply the maximum current, the magnet may lose its superconductivity. This phenomenon is called “quench” – a breakdown of superconductivity and leads to rapid heating of the magnet. Gradually increasing the current during training allows you to stabilize the internal structure of the superconductor and prepare it for operation at full capacity.
New types of magnets
The NICA project accelerator complex includes several complex devices: the superconducting synchrotrons Booster and Nuclotron, as well as the colliding beam accelerator-storage unit, which is actually a collider. All these devices use special magnets made of a superconducting niobium-titanium alloy. This material is already well mastered by industry and is widely used in such installations.
But here, in addition to the many problems that scientists have to solve, another one appears: fluctuations in energy consumption by the entire complex. During the cyclic operation of the accelerator, energy is sometimes consumed, and sometimes periodically returned to the city's power grid. This may not have a very good effect on other consumers of electricity in the city. On the other hand, voltage fluctuations in the city grid may also interfere with the stable operation of the accelerator itself.
Therefore, within the framework of the NICA project, it is planned to create a new type of magnet – an energy storage device. It will be made of the so-called high-temperature superconducting (HTSC) material ReBCO, or yttrium ceramics YBa2Cu3O7The task of the new magnet is to smooth out fluctuations in the network, working as a kind of buffer between the accelerator and the city's power grid.
Moreover, the HTSC material can operate at a much higher temperature than conventional superconductors. While a niobium-titanium alloy “operates” at a temperature of about 5 degrees Kelvin, HTSC “feels” great at a temperature 10 times higher. According to scientists, the use of HTSC magnets can reduce electricity costs for cooling by about 10 times compared to magnets made of niobium-titanium conductor.
Scientists from the Joint Institute for Nuclear Research in Dubna have proposed an innovative method for improving the properties of HTSC material. By irradiating it with heavy ions, they were able to increase the operating current in the HTSC wire by 3–4 times. This discovery will significantly reduce the consumption of expensive HTSC material in the manufacture of magnets for the new Nuclotron, which will make the project more cost-effective.
In the second stage of the NICA project, it is planned to replace all low-temperature superconductor (LTSC) magnets of the Nuclotron accelerator with HTSC magnets.
Hamlet Khodjibagian's team also developed a unique design for an energy cable. It allows magnet windings to be given a complex shape. The winding consists of several dozen tapes of high-temperature superconductors, which are spirally wound onto a cooling tube. The result is an energy cable capable of conducting a current of enormous strength.
After the launch of NICA, the team from the Laboratory of High Energy Physics of the Joint Institute for Nuclear Research plans to work on creating a magnet for the New Nuclotron synchrotron, another Nuclotron particle accelerator that has been operating at the institute since 1993.
The Future of HTS Magnets
And here we come to the part when fundamental scientific research (understood by few except scientists themselves) begins to turn into real practical projects, understandable to everyone. Magnets made of high-temperature superconductors are not some kind of highly specialized technology for colliders. Their potential is not just great. It is enormous.
According to Hamlet Khodjibagian, it will be difficult to imagine an industry in the future that will not use superconductivity. In addition to fundamental science, medicine, energy and transport, magnets with these properties will be needed in thermonuclear devices, in the space industry: in plasma engines, systems for protection against charged particles, systems for generating artificial magnetic fields and many other areas.
The science
In addition to colliders, HTS magnets can be used in other types of particle accelerators, such as synchrotrons and cyclotrons. These devices are used not only in high-energy physics, but also in the creation of new materials, in medical research, and even in archaeology. In addition, HTS magnets can help in the development of fusion reactors, bringing us closer to clean and virtually inexhaustible energy.
Medicine
MRI scanners with HTSC magnets will be able to provide even more detailed images, helping doctors make more accurate diagnoses. And in 2025, Hamlet Khodjibagian's team expects to launch the MSC-230 superconducting proton cyclotron. The facility is expected to help make a breakthrough in the treatment of oncological diseases using flash therapy.
The method involves rapid and precise delivery of an ultra-high dose of radiation to cancer-affected tissues. The approach allows for the harmful effects of radiation to be limited to the cancer-affected area during a session. Healthy tissues are not significantly damaged. In addition, the method potentially reduces the number of necessary sessions from 10–30 with conventional radiation therapy to 1–3 with a cyclotron.
Energy and transport
HTS magnets could make magnetic cushions (for trains, for example) efficient and affordable. And in the energy sector, more efficient energy storage devices, transformers, and power lines could emerge.
Industry
From more efficient induction heating in metallurgy to powerful microwave generators for a variety of applications.
In the space industry
Perhaps the most impressive example is protection from cosmic radiation by magnetic fields. A ship with passive protection would weigh hundreds of thousands of tonsand the only currently known way to reduce this weight is to use superconducting magnets to create magnetic fields. Another application is engines that use magnetic fields to accelerate plasma. And this is not science fiction, but real projects that scientists are already working on.
Looking to the future, it is difficult to find an area that will not be affected by this technology. High-temperature superconductor magnets may well become as revolutionary an invention as transistors or lasers, opening up new possibilities in all areas of our lives. And who knows, maybe right now, while working on magnets for the NICA collider, scientists are laying the foundation for technologies that will change the world in the coming decades.
